1. Field of the Invention
The invention relates in general to a temperature control apparatus, and more particular, to an ambient temperature control apparatus used for measuring a liquid crystal display. The ambient temperature control is operative to change the ambient temperature of the liquid crystal panel, so as to prevent it from affecting the ambient temperature of the measurement equipment; therefore, the precision of the measurement equipment is ensured.
2. Related Art of the Invention
Having the features of small volume, light weight, low driving voltage, low power consumption, and portability, the liquid crystal display products have been broadly applied. The application extends from products from daily life to high-end industrial production, including clocks, watches, computers, televisions, communication products, medical instrument, aviation transportation, industrial equipment, and special armaments. The high-quality liquid crystal displays tend to gradually replace the conventional color cathode ray tubes.
The conventional fabrication process of liquid crystal displays includes the following steps. A glass substrate is cleaned (pre-cleaning process). An indium tin oxide (ITO) conductive layer is formed on the glass substrate (pattern process). An alignment film is formed on the conductive layer (alignment and pattern transfer process). A spacer is formed between the two glass substrates. An insulating epoxy resin material is printed around the glass substrates (sealant coating process). The substrates are then adhered to each other (assembly and sealing process), and cut into individual dies. The liquid crystal is injected and the assembled substrates are then sealed by pressure, followed by the processes of corner rounding of the glass substrates, inspection of liquid crystal panel, adhesion of polarizer, and final inspection.
The above inspection process of the liquid crystal panel includes inspection of optical characteristics, such as the inspections of brightness, luminance and response time. As the luminance and response time of liquid crystal displays will vary according to ambient temperature, there is a need to perform the inspection of the ambient temperature dependent luminance and response time.
The conventional measurement apparatus of liquid crystal panels is shown in FIG. 1. Referring to FIG. 1, the measurement apparatus 100 includes at least a reaction chamber 102 and a photometer 104. In this example, a colorimeter is used. The liquid crystal panel 108 is fixed in the reaction chamber 102 via the panel fitting apparatus 106. The photometer 104 is used to measure the liquid crystal panel 108. Further, the measurement apparatus 100 includes a temperature control apparatus (not shown). When the temperature variation is required, the temperature of the reaction chamber 102 is either increased or decreased to perform the measurement.
However, the photometer 104 has a certain operating temperature range, for example, the operating temperature range for the above photometer (colorimeter) is about 23° C.±3° C. When the temperature variation of the liquid crystal panel 108 at either a higher or a lower temperature has to be measured, the temperature variation (increased or decreased) reflects the variation of the whole reaction chamber 102. As a result, the photometer 104 is frequently operated at a temperature out of the operating temperature range. The precision and accuracy of the measurement obtained therefrom is thus unreliable.